Java In-Memory URL

Ever needed an URL that reads its bytes from memory? This may be useful when you need to redirect a stream through some filter. Here is a Java class that does this stunningly simple. Mind that it is for a small amount of data only, all bytes (String data) must be in memory for this to work.

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import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.net.URI; import java.net.URL; import java.net.URLConnection; import java.net.URLStreamHandler; import java.util.Objects; public final class InMemoryUrl { public static URL build(String data) { Objects.requireNonNull(data); try { return URL.of( new URI("InMemory", "DummyPath", null), // protocol, path, reference new InMemoryUrlStreamHandler(data.getBytes())); } catch (Exception e) { throw new RuntimeException(e); } } private static class InMemoryUrlStreamHandler extends URLStreamHandler { private final byte[] data; public InMemoryUrlStreamHandler(byte[] data) { this.data = data; } @Override protected URLConnection openConnection(URL url) throws IOException { return new URLConnection(url) { @Override public void connect() throws IOException { connected = true; } @Override public long getContentLengthLong() { return data.length; } @Override public InputStream getInputStream() throws IOException { return new ByteArrayInputStream(data); } }; } } private InMemoryUrl() {} }

Here is a test main that you can use to try it out:

    public static void main(String[] args) throws Exception {
        final URL url = InMemoryUrl.build("This is a test with non-ASCII chars: ÄÜÖ äüö ß");
        final byte[] data = url.openConnection().getInputStream().readAllBytes();
        System.out.println(new String(data));
    }